Variable rate spring suspension



y 7, 1959 J; J. FODERMAIER VARIABLE RATE SPRING SUSPENSION I Sheets-Sheet 1 Filed April 5. 1955 INVENTOR. IJZZW .7 faiarmaz' r J. J. FODERMAIER VARIABLE RATE SPRING SUSPENSION Filed April 5, 1955 5 Sheets-Sheet 2 IN V EN TOR.

. J y 7, 1959 J. 4. FODERMAIER 2,893,475

VARIABLE RATE SPRING SUSPENSION Filed April 5, 1955 S I 5 Sheets-Sheet 3 x P a. INVENVTOR.

-I J22 f/ZZefWFdrks-r R BY- Y July 7, 1959 J.IJ. FODERMAIER VARIABLE RATE SPRING SUSPENSION I 5 Sheets-Sheet 4 Filed Apiil 5, 1955 By I July 7, 1959 J. J. FODERMAIER VARIABLE RATE SPRING SUSPENSION 5 Sheets-Sheet 5 Filed April 5, 1955 IN VEN TOR.

United States Patent VARIABLE RATE SPRING SUSPENSION .lolm J. Fodermaier, Birmingham, Mich., assignor to Chrysler Corporation, Highland Park, Mich., a corporationof Delaware Application April 5, 1955, Serial No. 499,307 3 11 Claims. Cl. 155-179 This invention relates to spring cushions made from sinuously shaped, flat, spring strips that have become known in the art as so-called zig-zag spring strips. It is the purpose of this invention to providea spring cushion formed from arched, sinuously shaped, spring strips wherein the cushion supporting surface may have an adjustable spring rate, that is, be adjusted to provide a different feel to the person seated upon the cushion supporting surface.

It is a primary object of this invention to provide a seat cushion formed from so-called zig-zag or sinuous- 1y shaped, arched, spring-strips wherein a means is provided, as a part of the cushion structure, to provide for variation in the effective span of the arched spring strips and thereby provide an adjustable rate cushion supporting surface.

It is a further object of this invention. to provide a seat cushion, back cushion, or the like, with means supported on the cushion frame to readily provide for the variation in hardness or softness of the cushion supporting surface.

It is a further object of this invention to provide an adjustable rate spring cushion formed from sinuously shaped, arched, spring strips wherein electrically and/or mechanically operated means, under the control of the cushion occupant, may be energized to effect variation in the cushion supporting rate and thus alter the cushion feel to satisfy the requirements of persons of different sizes and shapes or to vary the cushion rate so as to relieve cushion fatigue.

It is still another object of this invention to provide a variable rate cushion supporting surface that is simple in structure, readily adjustable, economical to manufacture, and one that may be incorporated wholly Within the cushion structure so that the improved variable rate cushion may be readily interchanged with spring cushions of conventional design.

It is still another object of this invention to provide a variable rate cushion supporting surface wherein the hardness and softness of the cushion supporting surface may be readily adjusted by operation of a simple push button or adjusting screw means located within easy reach of .the cushion occupant.

' Other objects and advantages of this invention will become readily apparent from a consideration of the following description and the related drawings wherein:

Fig. 1v is fragmentary perspective view of a structural seat unit embodying one form of this invention;

Fig. 2 is an end elevational view of the spring unit utilized in the seat cushion of the seat structure shown in justed to provide a relatively hard cushion supporting surface;

Fig. 5 is an enlarged, fragmentary, sectional elevational view similar to Fig. 4 but showing the associated elements in an altered relationship to provide a relatively soft cushion supporting surface;

Fig. 6 is a side elevational view of a cushion spring unit similar to that shown in Fig. 2 but embodying a modified form thereof;

Fig. 7 is a fragmentary upper plan elevational view of the cushion rate adjusting mechanism shown in the Fig. 6 cushion spring unit;

Fig. 8 is an upper plan elevational view of a cushion spring unit similar to that shown in Fig. 3 but disclosing a second modified form of this invention;

Fig. 9 is a side elevational view of the cushion spring unit shown in Fig. 8;

Fig. 10 is a fragmentary sectional elevational View of the control turnbuckle that is utilized in the Fig. 8 form of the invention, the view being taken along the line 10-10 of Fig. 8; and

Fig. 11 is a fragmentary sectional elevational view taken along the line 11--11 of Fig. 8 and illustrating the bearing means for the rotatable cushion spring element adjustable support.

Fig. 1 of the drawings shows a portion of a vehicle seat structure that comprises a base frame F that supports a seat cushion S and a seat back B. The frame F is mounted on tracks T to provide for fore and aft adjustment of the seat structure. While the present invention can be incorporated in a back cushion as well as seat cushion, it has been shown herein as applied to the seat cushion S. This invention specifically involves the spring unit of the seat, or back, and thus Figs. 2-5 show the spring unit of seat S without the associated padding or cover fabric.

The spring unit of the seat cushion S (see Figs. 2 and 3) comprises a front frame rail 14 having a pair of side rails 15 and 16 connected at their front ends to the opposite ends of the front rail 14. Side rails 15 and 16 are formed with upturned rear end portions 15a and 16a respectively that are connected to an elevated rear rail 17. Rear rail 17 is rotatably mounted on the upturned rear ends 15a. and 16a of the side rails 15 and 16. The rotatable connection between the rear rail 17 and the upturned ends 15a, 16a of the side rails 15, 16 is shown clearly in Figs. 3 and 11 respectively. Fixed in the ends of the side rail end portions 15a and 16a are cylindrical plugs 18 that each carry a radially extending pin 19. The pins 19 extend through circumferentially extending slots 20 formed in the end portions of the rear rail 17 which end portions are telescopically seated on the plugs 18. The pin and slot connections 19, 20 will limit the degree of free rotation of the rear frame rail 17 on the bearing plugs 18.

Arched between the front frame rail 14 and the rear frame rail 17 are a plurality of spring strips 24 that are each formed from connected, sinuously shaped, convolutions that extend in the same plane so as to provide a flat, narrow, longitudinally extensible spring strip. The spring strips 24 are each formed with a so-called fishmouth strip supporting section underlying each end of the strip load supporting surface. The fish-mouth at the front end of each spring strip 24 comprises an upper, downwardly and rearwardly extending, spring section 25 that is connected to the lower downwardly and forwardly sloping spring section 26. The lower free end of each of the lower sections 26 is anchored to the front frame rail 14 by a clamping clip 27. Border spring strips side rails 15 and 16. These springs 29 are formed from;

the same stock as spring strips 24 and are arched out- The fish-mout formed at the rear end of each spring strip 24 is composed of an upper, downwardly and forwardly sloping, spring section 31 and a connected lower, downwardly and rearwardly sloping, spring section 32. The next to the end straight leg portion 32a of the last spring convolution of (see Figs. 4 and 5) each section 32 is connected to the rear frame rail 17 by a clip 33 that provides a journal for the leg portion 32a. The last or free leg portion 32b of each section 32 is free to be swung into and out of engagement with the portion 33a of the associated spring supporting clip 33 as the rear frame rail 17 is rotated about its longitudinally extending axis. The means for rotating rail 17 is described hereafter.

Connected to the rotatable rear rail 17 is a lever arm 41. The free lower end of lever arm 41 is formed with an aperture to which is connected the rear end of a connecting rod 42. The forward end of connecting rod 42 is threaded as shown at 43 and the thread portion 43 of rod 42 is engaged with the threaded internal surface of the sleeve 44. Threaded sleeve 44 is connected by a drive transmitting slip clutch mechanism 45 to a shaft 46 that is drivingly connected to a reversible electric motor 47. Motor 47 is connected by the conductor cables 48 to a suitable source of electrical energy (not shown) such as the battery of a motor vehicle. Suitable motor control conductors (not shown) extend between the motor 47, the source of electrical energy therefor, and the control push buttons 49 and 50 (see Fig. 1) that are us'ed to select the direction of rotation and to effect energization of the motor 47. The motor 47 is pivotally mounted on a yoke-type support bracket 52 that includes motor mounting trunnions 53. The bracket 52 is fixedly connected to the front frame rail 14 by welding or the like.

With the arrangement heretofore described, it is thought to be obvious that as the motor 47 is energized, by depression of one of the push buttons 49, 50, the sleeve 44 will be screwed along the threaded portion 43 of connecting rod 42 and the lever 41 will be swung in one direction or the other to rotate the rear frame rail 17. At one limiting position of the rail 17, the lever 41 is in the forward position shown in Figs. 2 and 4 and the spring leg portion 32b is seated against the stop or abutment portion 33a of the anchor clip 33. Under such conditions the effective span of the spring strips 24 is a minimum and a relatively firm or hard cushion supporting surface is provided. If the other push button is depressed the lever 41 will be swung to its rearrnost position, as shown in Fig. 5, and then the effective span of the spring strips has been increased to the maximum and the spring portions 32b are now free of the abutments 33a so that the rear portion of each spring section 32 can hinge around its leg portion 32a that is journaled in a clip 33. Under these conditions a relatively soft cushion supporting surface is provided. It is obvious that the lever 41 can be stopped at any position intermediate its forward and rear positions to provide cushion supporting surfaces of varying degrees of hardness or softness.

From the foregoing description it is thought to be apparent that there is provided a cushion unit formed from conventional, sinuously shaped, spring strips wherein an economical, simple means is provided on the cushion frame for readily varying the rate of the cushion springs and the hardness and/ or softness of the cushion supporting surface. Due to mounting of the spring operating mechanism on the cushion frame this type of cushion unit can be interchanged with a standard spring cushion without any alteration whatever other than eflecting connection of the motor controls to a source of electrical energy and installation of the control push buttons 49, 50. The push buttons 49, 50 can be mounted on the seat frame F, as shown, or on any other conveniently located portion of the vehicle body or cushion supporting structure. Obviously, this invention can be applied to any seating structure whether it be vehicle mounted or stationary.

Furthermore, it will be noted from the dashed lines in Fig. 2 that the cushion supporting surface that has the load P applied thereto, at the location indicated, tends to deflect straight downward when the cushion surface is softened by rearward movement of lever 41. This type of deflection results from the use of a rear fishmouth portion 31, 32 in combination with the specific type of connection 33 between the fish-mouth 31, 32 and the rotatable rear frame rail 17. This provides the most comfortable supporting surface for there is no movement of the spine of the occupant fore and aft as the tension or rate of the cushion supporting surface is varied. With this invention the spring rate of the cushion may be varied to suit the occupant and still the occupants spine and back will be supported at all, times in the proper manner.

Another advantage of this invention is the fact that the rear frame rail may be located at an elevated position so that there is a maximum toe room for a person located on a seat positioned rearwardly of a seat embodying this invention. Also, there is no cumbersome mechanism located at the rear portion of the seat to interfere with the toe space beneath the rear portion of the seat cushion unit.

Figs. 6 and 7 show a modified form of this invention wherein manually operable means, rather than electrically operated means is provided to effect rotation of the rotatable rear frame rail 17. In all other respects, the spring unit shown in Figs. 6 and 7 is, identical to that shown in Figs. 1 through 5. The lever arm 41 that is connected to the rear frame rail 17 has the forward end of its connecting rod 42 connected to the male element 55 of a turnbuckle that also includes a sleeve-like female element 56. The female element 56 may be rotated by the knob 57 so that the internal threads on the female element 56 will effect forward and aft movement of the male turnbuckle element 55. A collar 58 is mounted on the female turnbuckle element 56 to anchor it in the frame front rail 14 in such a manner that the element 56 may be rotated while being prevented from moving forward and aft or sidewise of the rail 14. It is thought to be obvious that as the turnbuckle control knob 57 is rotated that the male element 55 of the turnbuckle will cause the connecting rod 42 to effect forward and aft swinging movement of the lever arm 41 for the. rotatable rear frame rail 17 and thereby vary the spring rate or hardness and/or softness of the cushion supporting surface provided by the arched spring strips 24. The form of the invention shown in Figs. 6 and 7 has all of the advantages pointed out with regard, to the Fig. 2 form of the invention and, in addition,'it is of simpler construction, of lower cost, and requires no alteration of the seat frame structure whatever in order to install this type of cushion unit in place of a conventional seat cushion such as may now be used in seat structures of the general type herein disclosed.

Figs. 8, 9 and 10, show a third form of this invention wherein cables and pulleys are used to actuate the rotatable rear frame rail 17. In this form of the invention the rotatable rear frame rail 17 is provided with a pair of lever arms 41' rather than a single lever arm 41 as was the case with the two previously described forms of this invention. Each of the lever arms 41' is connected by a flexible cable 61 to a pulley 62 that is mounted on a bracket 63 carried by the front frame rail 14 of the cushion unit. Each of the cables 61 passes around a pulley element 62 and has a portion thereof connected through the eye on the end of a female turnbuckle element 65. The mating female turnbuckle element-65 is rotatably mounted in a sleeve element 66. that is fixedly cO lnected t9, the cushion unit side rail 15 (see Fig. 10).

The female turnbuckle element 65 has a threaded internal surface which is threadably engaged with the male turnbuckle element 67. The male turnbuckle element 67 forms a shank portion of a shaft 68 that is rotatably mounted in the sleeve member 66. Shaft 68 is provided with a key portion 69 to effect rotation thereof. It is thought to be obvious that rotation of the shaft 68 will effect variation in the effective lengths of the cables 61 and thereby permit'swinging movement of the lever arms 41' in a forwardly or rearwardly direction. Due to the fact that flexible cables are used in this form of the invention, the swinging movement of the lever arms is not as positive in both directions as the type of action obtained with the forms of the invention shown in the Figs. 1 through 5 and Figs. 6 and 7 form of the invention wherein the connecting rod 42 is used. However, when a load is applied to the cushion supporting surface of the Figs. 8-10 form of the invention, the lever arms 41 will be caused to move rearwardly to the limit established by the lengths of the flexible cable 61 or the limits established -by the pin stop 19 that moves in the tube slot 20. All of the advantages claimed for the two aforedescrihed forms of this invention are likewise obtainable with the form of the invention shown in Figs. 8 through 10. The form of the invention shown in Figs. 8 through 10 is a simplified, low cost form, that does not necessitate any alteration whatever of the seat structure in which this type of cushion unit is to be incorporated.

I claim:

1. A spring cushion unit including opposed frame rails one of which is rotatable relative to the other about an axis extending longitudinally thereof, longitudinally extensible, load supporting, spring strip means extending between and anchored to said opposed rails, and means to cause rotation of said rotatable rail to effect variation in the effective length of the spring strip and thereby vary the deflection rate of the spring strip.

2. A spring cushion unit including opposed frame rails one of which is rotatable relative to the other about an axis extending longitudinally thereof, longitudinally extensible, load supporting, spring strip means extending between and anchored to said opposed rails, and means to cause rotation of said rotatable rail to effect variation in the length of the span bridged by said spring strip means and thereby vary the deflection rate of the spring strip.

3. A spring cushion unit comprising a pair of opposed frame rails one of which is rotatable relative to the other about an axis extending longitudinally thereof, longitudinally extensible, load supporting, spring strip means extending between and having the opposite end portions thereof connected to said frame rails, at least one of the ends of the spring strip means including a hinging section of substantially V-shaped cross sectional configuration that is arranged to underlie the spring strip load supporting surface and to connect one end portion of said spring strip to one of said frame rails, and means to effect rotation of the rotatable frame rail to effect variation in the effective length of the spring strip and thereby vary the deflection rate of the spring strip.

4. A seat spring cushion unit comprising a frame having a pair of opposed rails one of which is mounted for rotation about its longitudinally extending axis, longitudinally extensible, flat, sinuously convoluted, load supporting, spring strip means arched between and having the opposite end portions thereof connected to said opposed rails, the end portion of the spring strip means connected to the rotatable rail being formed to provide a hinging section of substantially V-shaped cross-sectional configuration which hinging section underlies the arched spring strip load supporting surface, and means to effect rotation of said rotatable frame rail to effect variation in the effective length of the spring strip and thereby vary the deflection rate of the spring strip.

5. A seat spring cushion unit comprising a frame having a pair of opposed rails one of which is mounted 6 for rotation about its longitudinally extending axis, longitudinally extensible, flat, sinuously convoluted, load supporting, spring strip means arched between and having the opposite end portions thereof connected to said opposed rails, the end portion of the spring strip means connected to the rotatable rail being formed to provide a hinging section of substantially V-shaped cross-sectional configuration which hinging section underlies the arched spring strip load supporting surface, and means to effect rotation of said rotatable frame rail comprising electrically operated means mounted on said frame and operably connected to said rotatable frame rail.

6. A spring cushion unit comprising a frame having a pair of opposed rails one of which is mounted for rotation about its longitudinally extending axis, longitudinally extensible, flat, sinuously convoluted, load supporting spring strip means arched between and having the opposite end portions thereof connected to said opposed rails, the end portion of the spring strip means connected to the rotatable rail being formed to provide a hinging section of substantially V-shaped cross-sectional configuration which hinging section underlies the arched spring strip load supporting surface, and means to effect rotation of said rotatable frame rail comprising screw operated means mounted on said frame and operably connected to said rotatable frame rail to effect variation in the effective length of the spring strip and thereby vary the deflection rate of the spring strip.

7. A seat spring cushion unit comprising a frame having a pair of opposed rails one of which is mounted for rotation about its longitudinally extending axis, longitudinally extensible, flat, sinuously convoluted, load supporting spring strip means arched between and having the opposite end portions thereof connected to said opposed rails, each end portion of the spring strip means being formed to provide a hinging section of substantially V-shaped cross-sectional configuration which hinging section underlies the arched spring strip load supporting surface, and means to effect rotation of said rotatable frame rail to effect variation in the effective length of the spring strip and thereby vary the deflection rate of the spring strip.

8. A seat spring cushion unit comprising a frame having a pair of opposed rails one of which is mounted for rotation about its longitudinally extending axis, longitudinally extensible, flat, sinuously convoluted, spring strip means arched between and having the opposite end portions thereof connected to said opposed rails, each end portion of the spring strip means being formed to provide a hinging section of substantially V-shaped cross-sectional configuration which hinging section underlies the arched spring strip load supporting surface, and means to effect rotation of said rotatable frame rail comprising a lever arm carried by said rotatable frame rail and connecting rod means connected between said lever arm and a mechanism mounted on the other of said rails for effecting adjustable movement of said connecting rod and rail lever arm to effect variation in the effective length of the spring strip and thereby vary the deflection rate of the spring strip.

9. A spring cushion unit comprising a frame having a pair of opposed rails one of which is mounted for rotation about its longitudinally extending axis, longitudinally extensible, flat, sinuously convoluted, spring strip means arched between and having the opposite end portions thereof connected to said opposed rails, each end portion of the spring strip means being formed to provide a hinging section of substantially V-shaped cross-sectional configuration which hinging section underlies the arched spring strip load supporting surface, and means to effect rotation of said rotatable frame rail, said spring strip end portion that is connected to the frame rotatable rail having a spring convolution portion inwardly from the free end thereof pivotally connected to said rotatable rail and the said free end of the spring end portion arranged to 7 be engaged with the rotatable frame rail in one of the limiting positions of rotational movement of the rotatable frame rail.

10. A seat spring cushion unit comprising a frame of substantially rectangular configuration formed from connected pairs of opposed front and rear rails and opposed side rails, said rear rail being rotatably mounted on said side rails for rotation about its longitudinally extending axis and being positioned at a level above that defined by the plane of the other rails, lever a'rm means carried by said rotatable rear rail and lever arm actuating means mounted on said frame and connected to said lever arm to effect rotation of said rear rail, and a plurality of longitudinally extensible, fiat, sinuously convoluted, load supporting, spring strips archedly connected between the opposed front and rear rails, said spring strips each being formed with end portions that underlie the strip load supporting portions and that are of substantially V-shaped cross-sectional configuration, the free end of the end portion connected to the rotatable rear frame rail being pivotally connected to said rear frame rail and arranged such that rotation of the rear frame rail elfects variation in the e ffectivelength of the span of the arched spring strips.

:11. A seat spring cushion unit comprising a frame of substantially rectangular configuration formed from connected pairs of opposed front and rear rails and opposed side rails, said rear rail being rotatably mounted on said side rails for rotation about its longitudinally extending axis and being positioned at a level above that defined by the plane of the other rails, lever arm means carried by said rotatable rear rail and lever arm actuating means mounted on said frame and connected to said lever arm to effect rotation of said rear rail, and a plurality of longitudinally extensible, fiat, sinuously convoluted, load supporting, spring strips archedly connected between the opposed front and rear rails, said spring strips each being formed with end portions that underlie the strip load supporting portions, the free end of the end portion connected to the rotatable rear frame rail being pivotally connected to said rear frame rail and arranged such that rotation of the rear frame rail effects variation in the effective length of the span of the arched spring strips.

References Cited in the file of this patent UNITED STATES PATENTS 346,622 Stair Aug. 3, 1886 1,724,590 Horn Aug. 13, 1929 2,657,740 Daniels et a1. Nov. 3, 1953 2,716,442 Larson et al Aug. 30, 1955 2,719,578 Flint Oct. 4, 1955 2,740,468 Gonia et a1 Apr. 3, 1956 

